Immobilization and intravenous anesthesia in a Sumatran rhinoceros (Dicerorhinus sumatrensis)

This paper reports in detail, for the first time, on two anesthetic procedures performed on a 15-yr-old, 530 kg, adult male Sumatran rhinoceros (Dicerorhinus sumatrensis). The anesthetic procedures were carried out in order to perform semen collection via electro-ejaculation, using well-established methods, and in order to examine and sample bilateral corneal opacities. Anesthesia for the first procedure was induced with a combination of 5 mg (0.0094 mg/kg) butorphanol tartrate and 5 mg (0.0094 mg/kg) detomidine hydrochloride administered intramuscularly. Subsequently, 0.74 mg (0.0014 mg/kg) etorphine and 3 mg (0.0057 mg/kg) acepromazine, with an additional 1.5 mg butorphanol (0.0028 mg/kg) and 1.5 mg (0.0028 mg/kg) detomidine, were administered intramuscularly. The second procedure was carried out using an intramuscular combination of butorphanol (0.019 mg/kg) and detomidine (0.019 mg/kg), followed by etorphine (0.0023 mg/kg) and acepromazine (0.009 mg/ kg). During the second procedure, the depth of anesthesia was managed with very small, supplemental intravenous doses of 50 mg ketamine (0.094 mg/kg). Sequential arterial blood gas analysis demonstrated respiratory acidosis with hypoxemia. Heart rate and respiratory rate ranged between 60-74 beats per minute (bpm), and 10-20 breaths per minute, respectively. Reversal after 100 min, with the intravenous administration of 150 mg (0.28 mg/kg) naltrexone and intravenous 20 mg (0.038 mg/kg) atipamezole, was uneventful and rapid, with the animal standing after 2 min. This combination provides satisfactory general anesthesia in this critically endangered species and will facilitate veterinary management of this species in captivity.